Telephonic communicating means



Oct. 8, 1929. 3 N H 1,730,761

TELEPHONIC COMMUNICATING MEANS Filed Sept. 8, 1927 anvemtoz PatentedOct. 8, 1929 'PATENT OFFICE GEORGE B. FRENCH, OF SOUTHAMPTON, NEW

COMPANY, INC., OF NEW YORK,'N.

YORK, ASSIGNOR TO FRENCH ELECTRIC Y., A CORPORATION OF NEW YORKTELEPHONIC COMMUNICATING MEANS Application filed September 8, 1927.Serial No. 218,130.

Owing to the loud noise of the motors driving an aeroplane it is notpossible for the pilot and the mechanician or observer to communicateorally in the ordinary manner.

It has accordingly been common practice to supply a telephonic apparatusfor such communication. Helmets are used to shut out the motor noise sofar as possible, and the transmitter and receiver are placed to themouth and ear respectively within the helmets.

Thisarrangement, while making it possible to communicate orally in anaeroplane, has the great disadvantage that the mouth of the speaker isconstantly imprisoned, so to speak. This prevents feeding and to someextent obstructs breathing, as well as creating embarrassment in case ofcoughing, sneezing, etc.

My present invention relates to means whereby telephonic communicationmay be effectively carried on in spite of great noise, such for instanceas that of aeroplane motors, machine shops and the like, while at thesame time leaving free the ears, nose, mouth and eyes of both persons incommunication.

Where my invention is employed on an aeroplane the customary helmetsneed not be used. To shut out the din of the motors the ears alone maybe simply closed by any appropriate means.

The invention is illustrated in the accompanying drawings wherein Figure1 is a perspective drawing of two persons furnished with my invention,and Figure 2 is a front elevation of my improved transmitter.

My invention comprises not only a special application of the transmitterand receiver of a telephonic combination, but also covers a novel formof transmitter which is capable of operation when in appropriate contactwith a speakers body but does not respond to ordinary acousticvibrations in the air. This form of transmitter is therefore, especiallyadapted to use in my special combination of transmitter and receiver ashereinafter described and claimed.

I have found that a properly constructed transmitter may be successfullyoperated by simply mounting it in contact with the pulmothoracic regionof the speaker, by which I mean the chest or neck, and preferably thelatter.

I have also found that if an ordinary telephonic receiver be clampedagainst the head, preferably against the temple or the mastoid bone, thesound will be transmitted directly to the inner ear. This permitsdampening or exclusion of undesirable noises from the outer and middleear, permitting exclusive reception of the sounds telephonicallytransmitted.

The specific means for carrying out my invention may take a greatvariety of forms, and in the drawings I have shown a preferredarrangement wherein any suitable form of transmitter 10 issecuredagainst the throat of the speaker by suitable means, such as a strap 11.

The receiver or receivers 12 is or are secured against the head, as, forinstance, the temples, of the person spoken to, by suitable means. Inthe drawing a strap 13 is used for this purpose.

The usual battery 14. is electrically connected with the transmitter andthe receiver or receivers by conductors 15, 16, in a well known manner.Obviously both persons may be equipped with both transmitter andreceiver so as to talk back and forth. This merely involves duplicationof what is shown in the drawing.

My invention may be carried out by using any well known form oftransmitter 10, but, to obtain perfect results, it is best to employ atransmitter which does not respond to aerial sound waves, but isoperated directly by the bodily vibrations incident to speech.

Accordingly I have invented a novel transmitter for this purpose apreferred form of which is shown in Figure My novel transmitter may bedescribe broadly as one which is provided with a dia phragm which is toothick to respond to aerial sound waves, while sensitive enough tooperate successfully under the direct influence of the more massivevibrations of a. portion of the speakers body in contact with suchdiaphragm.

In order the better to exclude all ordinary aerial sound waves,

the microphone is dispensed with, and instead my preferred transmitteremploys electro-magnetic coils and cores in combination with arelatively massive diaphragm of magnetic material such as soft iron ormild steel.

In order that the diaphragm used may be substantially free from theinfluence of aerial sound waves, I use a diaphra m of a form whichpermits free balancing 0 air pressures on its twosides. For this purposean elastic strip is substituted for the usual closed round diaphragm.

In Figure 2 the casing of the transmitter is shown at 17. Within'thiscasing are placed the high resistance coils 18 with their cores 19.These coils 18 are connected with the battery 14 and the receiver 12 bythe wires 15 and 16.

Over the coils or poles of the cores 19 extends my improved form ofdiaphragm consisting of a mere strip 20 of vibratory magnetic material,such as mild steel. This is so placed as to come into direct contactwith the body of the speaker when secured as shown in Figure 1 at 10.The strip 20 is made thicker than the ordinary telephonic diaphragm bothin order to provide a more efficient path for the magnetic lines offorce, and to prevent vibration due to external noises transmittedthrough the air. The free access of air to both sides of the strip 20also serves to preventvibration in response to ordinary acoustic waves.

What I claim is A- telephonic transmitter for attachment to the throat,comprising a relatively thin fiat casing, a magnet with a pair ofrelatively short magnet'poles of elongated cross-section mountedcentrally of said casing, a pair of elongated circuit coils about therespective magnet poles, and an armature formed from a narrow strip. ofrelatively thick magnetic material having its ends supported on andsecured to said casing so as to lie transversely of said ma net poleswith its sideedges free, the casing eingadapted to be attached flatagaint the throat with said armature extending longitudinally thereof,said armature being of such thickness as to respond to movements, of thethroat in articulate speech, but not to respond to air sound waves.

In testimony whereof I hereunto affix my signature.

GEORGE B.

